His parents were Walter of Salisbury and Sibilla de Chaworth.[1] Before 1141, Patrick was constable of Salisbury, a powerful local official but not a nobleman. That year, Patrick married his sister, Sibyl, to John fitzGilbert the Marshal, who had been a local rival of his, and transferred his allegiance from King Stephen to the Empress Matilda. This political move gained him his earldom, and the friendship of John the Marshal. Patrick's nephew, William the Marshal would go on to become regent of England during the minority of Henry III. For a time William served as a household knight with Patrick during Patrick's time as governor of Poitou.

The Earl of Salisbury also minted his own coins, struck in the county town of Salisbury during the so-called "baronial issues" of 1135–1153. Only four examples have survived, three of which are in the Conte collection.